Multi-Channel Inventory Reconciler

Reconciles stock across sales channels and classifies every discrepancy by CAUSE.

THE SILENT FAILURE. Channels report asynchronously, so a unit sold on one is still available on another until the slowest sync catches up. Naive reconcilers take the newest number and overwrite, which discards a legitimate concurrent sale and makes the count wrong in the other direction. Either way the store keeps selling stock it does not have, and the first symptom is a cancelled order.

Each difference is classified by cause — pending sync, unrecorded sale, unrecorded return, or genuine unexplained drift — because a single difference number is useless; the cause determines the action. UNEXPLAINED IS ITS OWN OUTCOME and is never absorbed into an explainable bucket. That absorption makes a real inventory leak look like ordinary lag.

A bug of exactly that kind was found in this product by an independent verifier before release: a balanced classification that short-circuited on the raw difference before considering the residual, reporting a real 2-unit gap as nothing to review. Fixed, mutation-proven, and the test fixture that had encoded the wrong behaviour was corrected too.

Quantities are integers. Deterministic and offline — the caller supplies snapshots as data.

VERIFIED: 31 tests, 10/10 mutations caught. Every mutation was observed FAILING before the source was restored — a test never seen to fail is a decoration.

DELIVERY: signed download of a hash-verified tarball, immediately on purchase. Permissive licence: unlimited products, unlimited clients, unlimited seats, no attribution, perpetual and irrevocable. One restriction, do not republish the source as source.

Interface

What you call, and what comes back. Types and signatures only — the implementation ships with the source.

  export function reconcileChannel( channel: ChannelSnapshot, source: SourceOfTruthSnapshot, events: LedgerEvent[], ): ChannelReconciliationLine;
  export function findConcurrentSaleConflicts(events: LedgerEvent[]): ConcurrentSaleConflict[];
  export function computeSafeListableQuantity( source: SourceOfTruthSnapshot, channelLines: ChannelReconciliationLine[], events: LedgerEvent[], ):;
  export function reconcileInventory(input: ReconcileInput): ReconcileResult;

  export type ChannelId = string;
  export type Sku = string;
  export type UnitId = string;
  export type LedgerEventType = "sale" | "return";